Comcast (Nasdaq: CMCSA), the country's largest cable operator, has expanded its usage-based broadband billing trial to its Maine cable systems, according to a report in Multichannel News. The trial caps users with a 300 GB monthly bandwidth allowance and charges them another $10 for every 50 GB they use. The same trial is underway in in a handful of other markets including Atlanta, Nashville and Charleston, S.C. Comcast maintains a full list of those markets. Read more